FREXP
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
frexp,
frexpf,
frexpl
--- extract mantissa and exponent from a double precision number
SYNOPSIS
#include <math.h>
double frexp(double num, int *exp);
float frexpf(float num, int *exp);
long double frexpl(long double num, int *exp);
DESCRIPTION
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here and the
ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.
These functions shall break a floating-point number
num
into a normalized fraction and an integral power of 2. The integer
exponent shall be stored in the
int
object pointed to by
exp.
RETURN VALUE
For finite arguments, these functions shall return the value
x,
such that
x
has a magnitude in the interval [½,1) or 0, and
num
equals
x
times 2 raised to the power *
exp.
If
num
is NaN, a NaN shall be returned, and the value of *exp is
unspecified.
If
num
is ±0, ±0 shall be returned, and the value of *exp shall be
0.
If
num
is ±Inf,
num
shall be returned, and the value of *exp is unspecified.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
isnan(),
ldexp(),
modf()
The Base Definitions volume of POSIX.1-2017,
<math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .